Chickens are like nature's steady-cams*. They posses a remarkable ability to keep their heads stable even as their bodies move around. And it all has to do with their eyes.
The anatomic feature is demonstrated to great effect in this newly released Mercedes commercial**, which is presumably for some stability feature? We're not really sure. We're here for the chickens:
Pretty cool, right? Chickens – like most birds – lack the eye-control necessary to keep their gaze fixed on a stationary object while the rest of their body is moving. In humans, these compensatory adjustments are handled by the vestibulo-ocular reflex (VOR), an involuntary eye-movement that (and I'm simplifying here***) keeps your vision stabilized when you move your head. Lacking the oculomotor control that we humans possess, chickens have evolved to offload these compensatory adjustments to the muscles of the head and neck, instead. The result, as you now know, looks like this:
Or like this:
Or, as famously demonstrated by Destin of Smarter Every Day, like this:
Lots of birds do this. If you've ever seen a pigeon bob its head as it walked around, you've seen a bird compensate for the movement of its body for the sake of its vision (or, in scientist speak, you've seen "an optokinetic response to stabilize the retinal image"). Remember the Rotate Your Owl video? Same thing.
** Weird: Fujifilm actually ran a very similar ad just a few months ago.
*** Oculomotor control, perhaps unsurprisingly, is a remarkably complex subject. For example: the eye-adjustments made possible by the vestibulo-ocular reflex are regarded by scientists who study these things as different from so-called "smooth pursuit eye movements," or "SPEMs," which describe the eye-movements that make it possible to track an object in motion (though both are made possible by similar neural pathways). It's the difference between reflexively compensating for your own movement and actively compensating for the movement of the object your tracking. Both of these smooth-eye movements are fundamentally different from the quick, jerky eye-movements known as "sacaddes." For a more technical look at oculomotor systems, see here.